diff --git a/content/bookmarks.js b/content/bookmarks.js
index 0334eca4..5b7a929e 100644
--- a/content/bookmarks.js
+++ b/content/bookmarks.js
@@ -233,8 +233,8 @@ function Bookmarks() //{{{
         "Set the default search engine",
         "string", "google",
         {
-            completer: function completer(filter) completion.runCompleter("search", filter, true),
-            validator: function validator(value)  completion.runCompleter("search", "", true).some(function ([s]) s == value)
+            completer: function completer(context) completion.search(context, true),
+            validator: function validator(value)   completion.runCompleter("search", "", true).some(function ([s]) s == value)
         });
 
     options.add(["preload"],
diff --git a/content/buffer.js b/content/buffer.js
index 3c494bb1..84c374ad 100644
--- a/content/buffer.js
+++ b/content/buffer.js
@@ -162,7 +162,7 @@ function Buffer() //{{{
                 ["1", "Show the link in the status line"],
                 ["2", "Show the link in the command line"]
             ],
-            validator: function (value) value >= 0 && value <= 2
+            validator: options.validateCompleter
         });
 
     options.add(["usermode", "um"],
diff --git a/content/completion.js b/content/completion.js
index 2998d86e..7d9fc5ba 100644
--- a/content/completion.js
+++ b/content/completion.js
@@ -952,7 +952,9 @@ function Completion() //{{{
         _runCompleter: function _runCompleter(name, filter)
         {
             let context = CompletionContext(filter);
-            context.fork.apply(context, ["run", 0, this, name].concat(Array.slice(arguments, 2)));
+            let res = context.fork.apply(context, ["run", 0, this, name].concat(Array.slice(arguments, 2)));
+            if (res) // FIXME
+                return { items: res.map(function (i) ({ item: i })) };
             while (context.incomplete)
                 liberator.threadYield(true, true);
             return context.allItems;
diff --git a/content/events.js b/content/events.js
index de4116d7..e27682eb 100644
--- a/content/events.js
+++ b/content/events.js
@@ -48,16 +48,8 @@ function AutoCommands() //{{{
         "List of autocommand event names which should be ignored",
         "stringlist", "",
         {
-            completer: function (value) config.autocommands.concat([["all", "All events"]]),
-            validator: function (value)
-            {
-                let values = value.split(",");
-                let events = config.autocommands.map(function (event) event[0]);
-
-                events.push("all");
-
-                return values.every(function (event) events.indexOf(event) >= 0);
-            }
+            completer: function () config.autocommands.concat([["all", "All events"]]),
+            validator: options.validateCompleter
         });
 
     options.add(["focuscontent", "fc"],
diff --git a/content/hints.js b/content/hints.js
index 2503b43f..99896d03 100644
--- a/content/hints.js
+++ b/content/hints.js
@@ -568,7 +568,7 @@ function Hints() //{{{
             {
                 return [[m, ""] for each (m in ["contains", "wordstartswith", "firstletters", "custom"])];
             },
-            validator: function (value) /^(contains|wordstartswith|firstletters|custom)$/.test(value)
+            validator: options.validateCompleter
         });
 
     options.add(["wordseparators", "wsp"],
diff --git a/content/liberator.js b/content/liberator.js
index 05d18ca8..1e3d9ccd 100644
--- a/content/liberator.js
+++ b/content/liberator.js
@@ -128,7 +128,7 @@ const liberator = (function () //{{{
                         ["b", "Bookmark bar"]
                     ].concat(!liberator.has("tabs") ? [] : tabopts);
                 },
-                validator: function (value) Array.every(value, function (c) c in config.guioptions || tabopts.some(function (a) a[0] == c))
+                validator: options.validateCompleter
             });
 
         options.add(["helpfile", "hf"],
diff --git a/content/mail.js b/content/mail.js
index 34167960..44ae50a9 100644
--- a/content/mail.js
+++ b/content/mail.js
@@ -218,7 +218,7 @@ function Mail() //{{{
 
                 return value;
             },
-            validator: function (value) /^(classic|wide|vertical|inherit)$/.test(value)
+            validator: options.validateCompleter
         });
 
     /*options.add(["threads"],
diff --git a/content/options.js b/content/options.js
index ae1ca578..5ffd6bb2 100644
--- a/content/options.js
+++ b/content/options.js
@@ -170,10 +170,10 @@ Option.prototype = {
 
     hasName: function (name) this.names.indexOf(name) >= 0,
 
-    isValidValue: function (value)
+    isValidValue: function (values)
     {
         if (this.validator)
-            return this.validator(value);
+            return this.validator(values);
         else
             return true;
     },
@@ -277,10 +277,9 @@ Option.prototype = {
 
         if (newValue == null)
             return "Operator " + operator + " not supported for option type " + this.type;
-        newValue = this.joinValues(newValue);
         if (!this.isValidValue(newValue))
             return "E474: Invalid argument: " + values;
-        this.set(newValue, scope);
+        this.setValues(newValue, scope);
     }
 }; //}}}
 
@@ -744,9 +743,13 @@ function Options() //{{{
                 if (!opt.value)
                     completions = [[option.value, "Current value"], [option.defaultValue, "Default value"]].filter(function (f) f[0]);
 
+                context.title = ["Option Value"];
                 if (completer)
                 {
-                    completions = completions.concat(completer(filter));
+                    let res = completer(context);
+                    if (!res)
+                        return;
+                    completions = completions.concat(res);
                     if (/list$/.test(option.type))
                     {
                         completions = completions.filter(function (val) opt.values.indexOf(val[0]) == -1);
@@ -762,7 +765,6 @@ function Options() //{{{
                     }
                 }
                 context.compare = function (a, b) 0;
-                context.title = ["Option Value"];
                 context.completions = completions;
             },
             literal: true,
@@ -989,6 +991,15 @@ function Options() //{{{
             return ret;
         },
 
+        // TODO: Run this by default?
+        validateCompleter: function (values)
+        {
+            let self = this;
+            let completions = completion.runCompleter(function (context) self.completer(context), "");
+            return Array.concat(values).every(
+                function (value) completions.some(function (item) item[0] == value));
+        },
+
         get store() storage.options,
 
         getPref: function (name, forcedDefault)
diff --git a/content/tabs.js b/content/tabs.js
index 5f770f2a..8b2886da 100644
--- a/content/tabs.js
+++ b/content/tabs.js
@@ -151,7 +151,7 @@ function Tabs() //{{{
                     ["2", "Always show tab bar"]
                 ];
             },
-            validator: function (value) value >= 0 && value <= 2
+            validator: options.validateCompleter
         });
 
     if (config.name == "Vimperator")
@@ -169,12 +169,7 @@ function Tabs() //{{{
                         ["paste", "P and gP mappings"]
                     ];
                 },
-                validator: function (value)
-                {
-                    return value.split(",").every(
-                        function (item) /^(homepage|quickmark|tabopen|paste|)$/.test(item)
-                    );
-                }
+                validator: options.validateCompleter
             });
 
         options.add(["newtab"],
@@ -192,12 +187,7 @@ function Tabs() //{{{
                         ["prefs", ":pref[erences]! or :prefs! command"]
                     ];
                 },
-                validator: function (value)
-                {
-                    return value == "all" || value.split(",").every(
-                        function (item) /^(addons|downloads|help|javascript|prefs|)$/.test(item)
-                    );
-                }
+                validator: options.validateCompleter
             });
 
         options.add(["popups", "pps"],
@@ -227,7 +217,7 @@ function Tabs() //{{{
                         ["4", "Open in the same tab unless it has a specific requested size"]
                     ];
                 },
-                validator: function (value) value >= 0 && value <= 4
+                validator: options.validateCompleter
             });
         // TODO: Add option, or only apply when go~=[nN]
         styles.addSheet("tab-binding", "chrome://*",
diff --git a/content/ui.js b/content/ui.js
index 0b0d0d18..8dff6fce 100644
--- a/content/ui.js
+++ b/content/ui.js
@@ -441,7 +441,7 @@ function CommandLine() //{{{
         "charlist", "sfl",
         {
             completer: function completer(filter) [k for each (k in completion.urlCompleters)],
-            validator: function validator(value) Array.every(value, function (v) v in completion.urlCompleters)
+            validator: options.validateCompleter
         });
 
     options.add(["history", "hi"],
@@ -475,28 +475,19 @@ function CommandLine() //{{{
 
                  return engines.map(function (engine) [engine.alias, engine.description]);
              },
-             validator: function validator(value)
-             {
-                 let ss = Components.classes["@mozilla.org/browser/search-service;1"]
-                                    .getService(Components.interfaces.nsIBrowserSearchService);
-
-                 return value.split(",").every(function (alias) {
-                     let engine = ss.getEngineByAlias(alias);
-                     return engine && engine.supportsResponseType("application/x-suggestions+json");
-                 });
-             }
+             validator: options.validateCompleter
          });
 
     options.add(["wildignore", "wig"],
         "List of file patterns to ignore when completing files",
         "stringlist", "",
         {
-            validator: function validator(value)
+            validator: function validator(values)
             {
                 // TODO: allow for escaping the ","
                 try
                 {
-                    new RegExp("^(" + value.replace(",", "|", "g") + ")$");
+                    new RegExp("^(" + value.join("|") + ")$");
                     return true;
                 }
                 catch (e)
@@ -521,12 +512,7 @@ function CommandLine() //{{{
                     ["list:longest",  "List all and complete common string"]
                 ];
             },
-            validator: function validator(value)
-            {
-                let self = this;
-                return value.split(",").every(function (opt)
-                    self.completer().some(function ([key]) key == opt))
-            },
+            validator: options.validateCompleter,
             checkHas: function (value, val)
             {
                 let [first, second] = value.split(":", 2);
@@ -545,10 +531,7 @@ function CommandLine() //{{{
                     ["sort", "Always sort the completion list"]
                 ];
             },
-            validator: function validator(value)
-            {
-                return value.split(",").every(function (item) /^(sort|auto|)$/.test(item));
-            }
+            validator: options.validateCompleter
         });
 
     /////////////////////////////////////////////////////////////////////////////}}}
@@ -1571,7 +1554,7 @@ function StatusLine() //{{{
                     ["2", "Always display status line"]
                 ];
             },
-            validator: function validator(value) value >= 0 && value <= 2
+            validator: options.validateCompleter
         });
 
     /////////////////////////////////////////////////////////////////////////////}}}